"I have to say that I feel muscles I was not even aware existed," the 40-year-old German told his official website michael-schumacher.de.

Fitness permitting, Schumacher has vowed to take injured Felipe Massa's place at Ferrari as from next month's European grand prix at Valencia.

The seven time world champion retired as a F1 race driver in 2006.

Schumacher said he was not surprised by his muscle stiffness. "It was clear you cannot test for a day after such a lot of time without feeling anything, and I am curious to see what will happen in the coming days."

His emergency training programme and medical checks are being headed by the Bad-Nauheim Sportklinic's Johannes Peil, who told the German news agency DPA that "we will only know if he can drive (at Valencia) when all the tests have been concluded".

Ferrari has requested that an exemption from the in-season test ban be granted so that Schumacher may also test the F60 in the near future.

While it is believed the FOTA group is happy to comply, whether Williams, Force India and the FIA will also agree is unknown.

Mercedes' Norbert Haug thinks the exemption should be granted. "If Michael had said he would come back on the condition that he gets one test, everyone would have agreed enthusiastically," the German said.

Luca di Montezemolo said he is confident all parties will indeed agree, telling Germany's Welt am Sonntag newspaper that it is an "absolutely exceptional case".

The Ferrari president also said the Maranello team is not expecting "miracles" from Schumacher after nearly three full seasons off the grid.